In situ polymerization of polypyrrole in oil body for efficient solar-driven freshwater collection

Solar-driven interfacial water evaporation can be exploited for freshwater generation with clean and pollution-free characteristics. The transport of water molecules from bulk water to the surface of the absorber is a key factor for efficient water evaporation. Herein, an oil body (OB), a spherical organelle extracted from safflower seeds, was used as supporting materials due to its low density and hydrophilic surface. After in situ polymerization of polypyrrole (PPy) in the interior of OB, an OB-PPy absorber with excellent photothermal performance and water transporting ability was obtained. When adding OB-PPy into sewage or seawater, it shows higher water evaporation rate and freshwater collection capabilities than PPy alone. The highest evaporation rate (2.11 kg m-2 h−1) and evaporation efficiency (92.02 %) can be obtained in OB-PPy containing rainwater. The freshwater collection rate can reach 1.38 kg m-2 h−1 when using a homemade freshwater collection device. Moreover, OB-PPy exhibits long term stability and reusability. Interestingly, we have found that OB-PPy lyophilized powder could absorb atmospheric water and produce freshwater from humid air. Therefore, OB-PPy holds great potential for solving the problem of freshwater resource shortage.